In tying down Hummels until 2017, Dortmund have secured the long-term services of a defender with rare versatility. No center-back has quite the same breadth of skills as the man who wears the No. 5 shirt for Germany. Click "Begin Slideshow" for a detailed analysis of the characteristics that make Hummels the most complete center-back in Europe.

Man-Marking

Alex Livesey/Getty Images

It's a modern cliche that defending is no longer what it used to be, but there is good reason to believe that in today's game, man-marking is rarely applied at the level it once was. Very few defenders have the ability to follow a striker, anticipate his movements and cut off the ball before it arrives.

Instead, many (like John Terry) have earned an on-field reputation for making last-ditch challenges. And while those interventions may be eye-catching, they beg the question: If the opponent was well-defended, why was such a risky challenge needed to stop him in the first place? Man-marking is not glamorous, and in the modern game the two players who can do at a high level are Thiago Silva and Mats Hummels.

Looking back over the last two Bundesliga seasons, in which Hummels has matured into an elite defender, Germany's best strikers have been stifled again and again by the Dortmund man. Last season, the top nine scorers in Germany—including Mario Gomez, Klaas-Jan Huntelaar, Raul, Lukas Podolski and Marco Reus—all failed to find the net against BVB.

This season, Hummels has furthered his credentials in the Champions League. Lethal strikers like Karim Benzema, Sergio Aguero, Edin Dzeko, and Gonzalo Higuain all were unable to hit the target against BVB in the group stage, as Hummels' strong partnership with Neven Subotic saw BVB advance to the Round of 16 as group winners.

Clean Tackling

Julian Finney/Getty Images

One of the most important aspects of defending is avoiding tackles: If one can anticipate a pass and intercept the ball, one eliminates the uncertainty of winning or losing a challenge. It is sometimes necessary to go into a 50-50 situation or to try to dispossess an opponent, and that is a skill in and of itself.

Many modern defenders, partly because they let their opponents get too far away, dive into challenges. Others are able to stay on their feet and win the ball back. The real measure of one's tackling ability is in how often a player fouls, and in particular, how often one receives bookings.

Ball Skills

In this day and age, center-backs need to be more than defenders; they need to be able to play the ball. With strikers pressing now more than ever, an unskilled defender can easily be exploited: He may win the ball, but that's of little use if he relinquishes possession moments later either in dribbling or punting it hopelessly forward (see Pepe). Hummels is a modern center-back, though, and has the skill required not only to shepherd the ball to safety, but to build the attack.

Statistically, there is little to say for Hummels' passing ability. This season, for example, he only has an 83.5 percent pass completion rate. However, the passes he attempts are much more ambitious than those attempted by many of his peers. As can be seen in the video above, he is very much a playmaker doubling as a defender. When in possession, he is comfortable directing the play.

While others like Gerard Pique and Holger Badstuber are also very skilled on the ball, neither has ever performed in the deep playmaking role quite like Hummels has. It should, however, be noted that this season, the Dortmund man has let the midfielders take on more ball-playing duties around the midfield line. Perhaps this is to ensure he is not caught out of position if the ball is lost. Still, if and when he is needed to make a dribble into the attacking half or play an accurate ball forward, Hummels can deliver the goods with utmost class.

Heading

Michael Steele/Getty Images

Set pieces have historically been a great leveler in football: A weaker team may stand little chance of scoring from free play, but given a set piece, all it takes is a good delivery and a brute in the box to nod in a potentially crucial goal. As such, size and heading ability are absolute must-have attributes in center-backs.

At 6'3", Hummels is a towering figure in the penalty box. In his young professional career, he's scored 10 goals from headers. And in the Bundesliga this season, he's won aerial duels by a ratio of approximately 2:1. Most strong teams concede a high percentage of their goals from headers, but Dortmund—despite not being as airtight at the back as they have in recent years—have let in just seven out of 20 goals conceded overall from headers. In the Champions League, that figure is just one out of five conceded.

There may be some who are better in the air than Hummels, but none with the breadth of his skill set. Thiago Silva comes close in terms of man-marking ability, but is less capable with the ball at his feet. Nemanja Vidic, Vincent Kompany and Giorgio Chiellini are strong defenders, but also lack ball skills and commit many more bad fouls. And for all their ability in possession, Sergio Ramos and Gerard Pique are downright sloppy in the challenge. Judging from heading, tackling, man-marking and all skills, there is no center-back in Europe more complete than Mats Hummels.